1. Field of Invention
This invention relates to a device for needle safety, specifically to a device to protect from injury due to accidental needle sticks.
2. Discussion of Prior Art
Needle stick injuries are one of the most common job related injuries among health care workers, and may result in transmission of blood-born pathogens. The risk is greater due to the increasing prevalence of serious infectious diseases in the general population such as Hepatitis B, Hepatitis C, and HIV. Needle stick injuries can occur during use of a range of medical devices, including hypodermic syringes, blood collection needle sets (“butterfly syringes”), intravenous catheters, and other intravenous infusion equipment.
More than 8 million health care workers in the United States work in hospitals and other health care settings. Estimates indicate that 600,000 to 800,000 needle stick and other percutaneous injuries among health care workers occur annually. Percutaneous injury (e.g., needle stick) was associated with 89% of the documented transmissions of HIV to healthcare workers between 1985 and 1999. Approximately 38% of percutaneous injuries occur during use of a sharp device and 42% occur after use and before disposal.1 
There is an ongoing need for a safe and effective needle cap device because it has the potential to save lives. This need has been recognized, and has since become a law. Congress passed the Needle Stick Safety and Prevention Act directing OSHA to revise the blood-borne pathogens standard. This revision established in greater detail the requirement that employers identify and make use of effective and safer medical devices. The OSHA revision was published on Jan. 18, 2001, and became effective on Apr. 18, 2001.
Directives relating to safety devices to prevent needle sticks published by the National Institute for Occupational Safety and Health include the following desirable characteristics:                1. The safety feature is an integral part of the device.        
2. The device preferably works passively (i.e., it requires no activation by the user).                3. The user can easily tell whether the safety feature is activated.        4. The safety feature remains protective through disposal.        5. The device performs reliably.        6. The device is easy to use and practical.        7. The device is safe and effective for patient care1.        
There are more than 100 products to reduce the risk of accidental needle sticks currently on the market, (U.S. Pat. No. 5,630,803, U.S. Pat. No. 6,015,397, U.S. Pat. No. 5,069,669, U.S. Pat. No. 5,295,972, U.S. Pat. No. 5,250,031, U.S. Pat. No. 5,411,492, U.S. Pat. No. 5,407,070, U.S. Pat. No. 5,385,550, U.S. Pat. No. 5,356,387, and U.S. Pat. No. 5,964,731 for example) but studies have shown that the users are dissatisfied with currently available needle safety devices, and in some cases that the incidence of accidental needle sticks rises with the use of these safety needles2. Recapping of needles, although prohibited by policy in many workplaces, is a major reason for needle stick injuries.
The needle safety devices fall into two categories of action; active and passive. The majority of devices use the active mechanism. Active devices require the health care worker to activate the safety mechanism. Failure to activate leaves the worker unprotected. Proper use by the health care worker is the primary factor in the effectiveness of these devices.
Several types of active needle safety devices have been proposed. Since these devices rely on the worker for activation of the safety mechanism there is a chance that the worker will be left unprotected. Some of these devices require the worker to place his/her fingers in front of the needle which can be a safety hazard.
Very few needle safety devices utilize passive activation. Passive safety devices do not need to be activated by the health care worker. They remain in effect before, during, and after use. Passive devices enhance the safety design and are more likely to have a greater impact on prevention than active devices.
There are a few passive needle safety devices that have been proposed. These devices are very complex with many parts, and most cannot be used with standard injection devices. This means that they are expensive to manufacture. Also, in many cases, the user will also have to modify their injection technique.
All of the needle safety devices suffer from a number of disadvantages:                (a) Most devices utilize an active system to activate the safety mechanism. The safety mechanism is not automatically in effect. If the worker fails to activate the system or activates the system incorrectly, the safety mechanism will not be in effect and the worker will be left unprotected.        (b) Most devices have many complex parts, which are difficult and expensive to manufacture.        (c) Most devices modify the entire syringe. This is very costly to manufacture, and it may result in a modification of injection technique.        (d) Most devices are non-compatible with other types of injection devices.        (e) Most devices cannot be unlocked for reuse.        (f) The devices do not meet all of OSHA and FDA suggested criteria for needle safety devices:                    1) The safety feature is not an integral part of the device.            2) The devices do not work passively.            3) The user cannot easily tell whether the safety feature is activated.            4) The safety feature does not remain protective through disposal.            5) The device is not easy to use and not always practical.            6) The device is not always safe and effective for patient care.                        